Synchronizing a channel codec and vocoder of a mobile station

ABSTRACT

In one embodiment, the present invention includes a method for maintaining a vocoder and channel codec in substantial synchronization. The method may include receiving a configuration message that includes rate information and an effective radio block identifier at a mobile station, coding a current radio block via a vocoder and channel codec, configuring an encoding portion of the vocoder and channel codec with the rate information after performing the coding, and then coding the effective radio block using the rate information. Other embodiments are described and claimed.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

The present application claims priority from, and is a divisional of,U.S. patent application Ser. No. 11/253,469 filed on Sep. 23, 2005,assigned to the assignee of the present invention, the disclosure ofwhich is herein specifically incorporated by this reference in itsentirety.

FIELD OF THE INVENTION Background

The present invention relates to data processing and more particularlyto speech processing in a wireless device.

Wireless devices or mobile stations such as cellular handsets and otherwireless systems transmit and receive representations of speechwaveforms. A physical layer of a cellular handset typically includescircuitry for performing two major functions, namely encoding anddecoding. This circuitry includes a channel codec for performing channelencoding and decoding functions and a vocoder for performing voiceencoding and decoding functions. The vocoder performs source encodingand decoding on speech waveforms. Source coding removes redundancy fromthe waveform and reduces the bandwidth (or equivalently the bit-rate) inorder to transmit the waveform in real-time. The channel codec increasesredundancy in the transmitted signal to enhance the robustness of thetransmitted signal. Synchronizing these two functions allows the systemto operate properly.

A number of different wireless protocols exist. One common protocol isreferred to as global system for mobile communications (GSM). In a GSMsystem, the vocoder operates on blocks of speech data that are 20milliseconds (ms) in duration. The channel codec transmits and receivesdata every 4.615 ms. Since the speech encoder (i.e., vocoder) serves asa data source to the channel encoder/modulator (i.e., channel codec) andthe speech decoder (i.e., vocoder) serves as the data sink for thechannel demodulator/decoder (i.e., channel codec), the vocoder andchannel codec should be maintained in synchronization.

Further, the speech encoder should deliver data to the channel encoderwith sufficient time margin to complete channel encoding and modulationoperations before the time at which the data are transmitted over theair. Further complicating the issue are limits on the round-trip delayof the overall communications link. Hence, the vocoder cannot deliverthe data too early lest the delay budget (such as that set forth by theEuropean Telecommunications Standards Institute (ETSI)) be violated, andcannot deliver data too late lest the data be discarded. As a practicalmatter, the later the vocoder delivers data to the channel codec, theharder a digital signal processor (DSP) must work to complete all signalprocessing on schedule, thus creating a greater system load.

Adaptive multi-rate (AMR) vocoders have been introduced recently incertain cellular communication standards, such as GSM and WCDMA. AMRvocoders support multiple source rates, and compared to other vocoders,provide some technical advantages. These advantages include moreeffective discontinuous transmission (DTX) because of an in-bandsignaling mechanism, which allows for powering down a transmitter when auser of a cellular phone is not speaking. In such manner, prolongedbattery life and reduced average bit rate, leading to increased networkcapacity is provided. AMR also allows for error concealment.

In a system supporting AMR, the bit rate of network communications canbe controlled by the radio access network depending upon air interfaceloading and the quality of speech conditions. To handle such differentbit rates, the network will send configuration messages to a cellularphone to control its transmission at a selected bit rate. During an AMRvoice call, the network may send a message to the mobile station tochange the AMR configuration (e.g., source rate). Since both the channelcodec and vocoder use this information, careful synchronization isneeded between the codec and vocoder during AMR configuration changes.

Accordingly, methods and apparatus to maintain synchronization betweenchannel codec and vocoder would improve performance of a mobile station.

SUMMARY OF THE INVENTION

In one embodiment, the present invention includes a method formaintaining a vocoder and channel codec in substantial synchronization.The method may include receiving a configuration message that includesrate information and an indicator corresponding to an effective radioblock for application of the rate information at a mobile station,coding a current radio block via a speech encoder and a channel encoder,configuring the speech encoder and the channel encoder with the rateinformation after performing the coding, and then coding the effectiveradio block with the rate information. In other embodiments, a differentpriority of configuration activities may be implemented to maintain thevocoder and channel codec in substantial synchronization.

Other embodiments may be implemented in an apparatus, such as anintegrated circuit (IC). The IC may include a vocoder to encode speechblocks and a channel encoder coupled to the vocoder to channel encodethe encoded speech blocks. In various embodiments, configurationinformation may be applied to the vocoder and channel codec to maintainthem in substantial synchronization. More specifically, theconfiguration information may be applied according to a priority tomaintain the synchronization, while at the same time performing codingand decoding operations on outgoing and incoming radio blocks inaccordance with rate information, for example, indicated by a network.As an example, the IC may take the form of a digital signal processor.

Embodiments of the present invention may be implemented in appropriatehardware, firmware, and software. To that end, a method may beimplemented in hardware, software and/or firmware to synchronize achannel codec and vocoder, e.g., of a wireless device. The method mayperform various functions including receiving a configuration messagefrom a network at a wireless device and configuring the channel codecand vocoder based upon the configuration message according to a priorityso that the channel codec and the vocoder operate in synchronization.For example, the priority may cause the device to schedule encodingconfiguration prior to decoding configuration. Furthermore, the prioritymay further schedule the encoding configuration before transmission ofan effective radio block for the new configuration, and schedule thedecoding configuration after decoding of a radio block immediately priorto the effective radio block.

In one embodiment, a system in accordance with an embodiment of thepresent invention may be a wireless device such as a cellular telephonehandset, personal digital assistant (PDA) or other mobile device. Such asystem may include a transceiver, as well as digital circuitry. Thedigital circuitry may include circuitry such as an IC that includes atleast some of the above-described hardware, as well as control logic toimplement the above-described methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an audio signal processing path in awireless device in accordance with an embodiment of the presentinvention.

FIG. 2A is a time division multiple access (TDMA) frame structure of amulti-slot communication standard.

FIG. 2B is a multi-frame structure used for a traffic channel of amulti-slot communication standard.

FIG. 3 is a flow diagram of a configuration method for uplink encodersin accordance with one embodiment of the present invention.

FIG. 4 is a flow diagram of a configuration method for downlink decodersin accordance with one embodiment of the present invention.

FIG. 5 is a timing diagram for reconfiguration of a vocoder and channelcodec in accordance with an embodiment of the present invention.

FIG. 6 is a block diagram of a system in accordance with one embodimentof the present invention.

DETAILED DESCRIPTION

Referring to FIG. 1, shown is a block diagram of a signal processingpath in a wireless device in accordance with an embodiment of thepresent invention. Such a transmission chain may take the form ofmultiple components within a cellular handset or other mobile station,for example. As shown in FIG. 1, an application specific integratedcircuit (ASIC) 15 may include both baseband and radio frequency (RF)circuitry. The baseband circuitry may include a digital signal processor(DSP) 10. DSP 10 may process incoming and outgoing audio samples inaccordance with various algorithms for filtering, coding, and the like.

While shown as including a number of particular components in theembodiment of FIG. 1, it is to be understood that DSP 10 may includeadditional components and similarly, some portions of DSP 10 shown inFIG. 1 may instead be accommodated outside of DSP 10. It is also to beunderstood that DSP 10 may be implemented as one or more processingunits to perform the various functions shown in FIG. 1 under softwarecontrol. That is, the functionality of the different components shownwithin DSP 10 may be performed by common hardware of the DSP accordingto one or more software routines. As further shown in FIG. 1, ASIC 15may further include a microcontroller unit (MCU) 65. MCU 65 may beadapted to execute control applications and handle other functions ofASIC 15.

DSP 10 may be adapted to perform various signal processing functions onaudio data. In an uplink direction, DSP 10 may receive incoming voiceinformation, for example, from a microphone 5 of the handset and processthe voice information for an uplink transmission. This incoming audiodata may be converted from an analog signal into a digital format usinga codec 20 formed of an analog-to-digital converter (ADC) 18 and adigital-to-analog converter (DAC) 22, although only ADC 18 is used inthe uplink direction. In some embodiments, the analog voice informationmay be sampled at 8,000 samples per second or 8 kHz. The digitizedsampled data may be stored in a temporary storage medium (not shown inFIG. 1). In some embodiments, one or more such buffers may be present ineach of an uplink and downlink direction for temporary sample storage.

The audio samples may be collected and stored in the buffer until acomplete data frame is stored. While the size of such a data frame mayvary, in embodiments used in a time division multiple access (TDMA)system, a data frame (also referred to as a “speech frame”) maycorrespond to 20 ms of real-time speech (e.g., corresponding to 160speech samples). In various embodiments, the input buffer may hold 20 msor more of speech data from ADC 18. As will be described further below,an output buffer (not shown in FIG. 1) may hold 20 ms or more of speechdata to be conveyed to DAC 22.

The buffered data samples may be provided to an audio processor 30 a forfurther processing, such as equalization, volume control, fading, echosuppression, echo cancellation, noise suppression, automatic gaincontrol (AGC), and the like. From front-end processor 30 a, data isprovided to a vocoder 35 for encoding and compression. As shown in FIG.1, vocoder 35 may include a speech encoder 42 a in the uplink directionand a speech decoder 42 b in a downlink direction. Vocoder 35 thenpasses the data to a channel codec 40 including a channel encoder 45 ain the uplink direction and a channel decoder 45 b in the downlinkdirection. From channel encoder 45 a, data may be passed to a modem 50for modulation. The modulated data is then provided to RF circuitry 60,which may be a transceiver including both receive and transmit functionsto take the modulated baseband signals from modem 50 and convert them toa desired RF frequency (and vice versa). From there, the RF signalsincluding the modulated data are transmitted from the handset via anantenna 70.

In the downlink direction, incoming RF signals may be received byantenna 70 and provided to RF circuitry 60 for conversion to basebandsignals. The transmission chain then occurs in reverse such that themodulated baseband signals are coupled through modem 50, channel decoder45 b of codec 40, vocoder 35 (and more specifically speech decoder 42b), audio processor 30 b, and DAC 22 (via a buffer, in some embodiments)to obtain analog audio data that is coupled to, for example, a speaker 8of the handset.

For purposes of further illustration, the discussion is with respect toa representative GSM/GPRS/EDGE/TDMA system (generally a “GSM system”).However, other protocols may implement the methods and apparatusdisclosed herein, particularly where shared configuration information isto be updated in both voice and channel codecs.

A GSM system makes use of a TDMA technique, in which each frequencychannel is further subdivided into eight different time slots numberedfrom 0 to 7. Referring now to FIG. 2A, shown is a timing diagram of amulti-slot communication 80. As shown in FIG. 2A, multi-slotcommunication 80 includes a TDMA frame 85 having eight time slots inwhich the frequency channel of TDMA frame 85 is subdivided. Each of theeight time slots may be assigned to an individual user in a GSM system,while multiple slots can be assigned to one user in a GPRS/EDGE system.A set of eight time slots is referred to herein as a TDMA frame, and maybe a length of 4.615 ms.

A 26-multiframe is used as a traffic channel frame structure for therepresentative system. Referring now to FIG. 2B, shown is a multiframecommunication 90 that includes a 26-multi-frame formed of 26 individualTDMA frames T0-I25. As shown in FIG. 2B, the first 12 frames (T0-T11)are used to transmit traffic data. A frame (S12) is used to transmit aslow associated control channel (SACCH), which is then followed byanother 12 frames of traffic data (T13-T24). The last frame (I25) staysidle. Note that the SACCH and idle frame can be swapped. The totallength of a 26-frame structure is 26*4.615 ms=120 msec.

In a GSM system, a speech frame is 20 msec while a radio block is 4 TDMAframes, which is 4*4.615=18.46 msec. Data output from a speech codec isto be transmitted during the next radio block, and every three radioblocks, the TDMA frame or radio block boundary and the speech frameboundaries are aligned.

Consider a first radio block N, e.g., frame 0 to frame 3 (T0-T3) offrame structure 90 of FIG. 2B. In an uplink side, a channel encoding(CHE) for block N should be completed before the transmit slot of thefirst frame of the radio block, frame 0 in this case. Similarly, speechencoding (SPE) for block N should be completed before the channelencoder starts so that the payload data for block N is ready to beencoded. In a downlink side, channel decoding (CHD) for block N maystart after receipt of the last frame of the radio block, frame 3 inthis case, while speech decoding (SPD) for block N may start afterchannel decoding is completed. In various embodiments, thissynchronization between channel codec and vocoder may be maintained forall blocks in order to permit proper system execution.

During an AMR voice call, the network may send a message to the mobilestation to request the mobile station to change its AMR configuration.Typically, the configuration message includes rate information (e.g., anew transmission rate) and an identification of a given radio block(corresponding to a transmission time) at which the rate information isto take effect. In order to apply a new AMR configuration, a softwareroutine may be implemented. In one embodiment the routine, AMR configure(AMRCFG), may be used to apply AMR configuration for uplink anddownlink. For ease of discussion, configuration for the uplink side maybe also referred to herein as ACU and configuration for the downlinkside may be also referred to herein as ACD.

In various embodiments, configuration information may be appliedaccording to task execution priorities within the cellular transmissioncycle. For example, in one embodiment a task execution priority mayproceed as follows: channel encoding may have a highest priority;configuration (i.e., in uplink and downlink directions) may have a nextpriority; channel decoding may have a next lower priority; and finally,speech encoding/decoding may have a lowest priority. While describedwith this particular priority in one embodiment, it is to be understoodthat other priorities may be present in other embodiments. Furthermore,in different embodiments task executions may be moved relative to agiven execution priority for multiple radio blocks. That is, in someembodiments tasks for a first block may be performed before tasks(including configuration/reconfiguration) for a subsequent radio block.

Consider now an example where a network sends a configuration message,e.g., an AMR configuration message to a cellular phone. Furthermore,assume that the message instructs the phone to apply the newconfiguration information to a next radio block N+1. At a frameinterrupt for the first TDMA frame of a current radio block N, a DSPkernel schedules channel encoding for block N and ACU. Accordingly,channel encoding for block N and reconfiguration of the speech encoderand channel encoder may be performed during transmission of block N. Atthe frame interrupt for the first TDMA frame of radio block N+1, the DSPkernel schedules channel encoding for block N+1 (implicitly, speechencoding for block N+1 occurs prior to the channel encoding). Because ofthe task execution priority, the execution sequence for this example mayoccur as follows:

CHE for block N;

ACU (AMRCFG for uplink);

SPE for block N+1; and

CHE for block N+1.

In various embodiments, ACU may be performed such that the newconfiguration is applied to the speech encoder first and then to thechannel encoder so that the speech encoder and channel encoder aresynchronized.

Referring now to FIG. 3, shown is a flow diagram of a method inaccordance with one embodiment of the present invention. As shown inFIG. 3, method 100 may be used to configure a speech encoder and channelencoder in the uplink direction. While the scope of the presentinvention is not so limited, in some embodiments these encoders may beconfigured when a mobile station receives updated rate information suchas may be received from a network implementing an adaptive multi-ratesystem that supports different source rates.

Still referring to FIG. 3, method 100 may begin by receiving new rateconfiguration information (block 110). For example, a network maydetermine that, due to network conditions, the mobile station shouldswitch to a new bit rate. Accordingly, the network may send the new rateconfiguration information that is to be implemented beginning at apredetermined radio block, for example, a next radio block (e.g., N+1)to be encoded in the mobile station. In some embodiments, theconfiguration information may be stored in a protocol stack of themobile station.

Next, the current radio block (e.g., radio block N) may be channelencoded using the channel encoder (block 120). As described above, thischannel encoding occurs prior to transmission of radio block N.Furthermore, in some embodiments the channel encoding may be scheduledto occur upon receipt of a frame interrupt signal received just prior tothe beginning of a transmission period of radio frame N.

To maintain synchronization between speech encoder and channel encoder,the new configuration information may be scheduled to be applied to thespeech encoder at a predetermined time after receipt of this frameinterrupt signal. That is, to maintain synchronization, the channelencoding of radio block N should occur using the prior configurationinformation. Furthermore, the channel encoding may be executed with ahigher priority than reconfiguration.

Accordingly, at the predetermined time, the new configurationinformation may be applied to the speech encoder (block 130). Forexample, in some embodiments the new configuration information may beapplied at a predetermined time after receipt of the first frameinterrupt signal for radio block N. However the new configurationinformation may be applied to the speech encoder at various other timeinstants. Preferably, however, the new configuration information isapplied after channel encoding radio block N.

Still referring to FIG. 3, next the new configuration information may beapplied to the channel encoder (block 140). For example, the newconfiguration information may be applied to the channel encoderimmediately after applying the new configuration information to thespeech encoder. While described with this order in the embodiment ofFIG. 3, in other implementations the channel encoder may be reconfiguredwith the new configuration information prior to the speech encoder.However, in various embodiments the configuration information should beapplied to both encoders prior to the time that either of the encodersis to encode radio block N+1.

Finally, radio block N+1 may be encoded using the new configurationinformation in the speech encoder and channel encoder (block 150). Insome embodiments, the speech encoding for radio block N+1 may beginduring transmission of radio block N. For example, this speech encodingmay begin within a third or fourth TDMA frame of radio block N.

In the downlink side, configuration/reconfiguration of a channel decoderand speech decoder may be performed prior to decoding activities for theblock in which configuration information is to be effected. Thus,configuration/reconfiguration may be performed after decoding of aprevious block (e.g., block N) and during transmission of the radioblock in which the new configuration information is to be effected(e.g., a block N+1), but prior to decoding operations for the block.Then, after receiving the last burst in block N+1, the DSP kernel mayschedule configuration events, along with channel decoding and speechdecoding. Because of the task execution priority, the execution sequencefor this example may occur as follows:

ACD (AMRCFG for downlink);

CHD for block N+1; and

SPD for block N+1.

In various embodiments, ACD may be performed such that the new AMRconfiguration is applied to the channel decoder first and then to thespeech decoder so that the channel decoder and speech decoder aresynchronized.

Referring now to FIG. 4, shown is a block diagram of a configurationmethod for downlink decoders in accordance with one embodiment of thepresent invention. As shown in FIG. 4, method 200 may be used toconfigure a channel decoder and a speech decoder with, for example, newrate configuration information.

As shown in FIG. 4, method 200 may begin by receiving new rateconfiguration information for a next radio block (i.e., N+1) to beprocessed by the decoders (block 210). As one example, the configurationinformation may be received prior to transmission of a current radioblock (i.e., block N). However, the configuration informationalternately may be received sometime during transmission of radio blockN. As described above, the new rate configuration information may bestored in the protocol stack of the mobile station. Next, the newconfiguration information may be applied to the channel decoder at apredetermined time (block 220). While reconfiguration of the channeldecoder may occur at various times with respect to transmission of radioblocks, in some embodiments the reconfiguration may occur duringtransmission of radio block N+1. That is, reconfiguration of the channeldecoder may occur during transmission of the block that is to beprocessed with the new configuration information. Still further, whilethis reconfiguration may occur at various instants within this radioblock, in some embodiments reconfiguration may be scheduled with respectto receipt of a frame interrupt for a third TDMA frame within the radioblock N+1.

Thereafter, the new configuration information may be applied to thespeech decoder (block 230). For example, in some embodimentsreconfiguration of the speech decoder may occur immediately followingreconfiguration of the channel decoder. Finally, radio block N+1 may bedecoded using the new configuration information in the channel decoderand speech decoder (block 240). In various embodiments, channel decodingmay occur for the radio block upon receipt of the last TDMA frame (i.e.,T7) for radio block N+1. Upon completion of the channel decoding, speechdecoding may then be performed. While described with this particularprocess in the embodiment of FIG. 4, it is to be understood the scope ofthe present invention is not so limited and configuration orreconfiguration of speech and channel decoders may vary in differentembodiments.

Referring now to FIG. 5, shown is a timing diagram for reconfigurationof a vocoder and channel codec in accordance with an embodiment of thepresent invention. As shown in FIG. 5, various coding and configurationevents are shown with respect to a transmission sequence 48 thatincludes transmission of a first radio block N followed by a secondradio block N+1 on an antenna of the cellular telephone. As shown inFIG. 5, first speech encoding of radio block N occurs in speech encoder42 a. Following completion of speech encoding, the encoded speech datais provided to channel encoder 45 a for channel encoding of the radioblock N data. As shown in FIG. 5, the channel encoding for block N maybe completed prior to transmission of the first TDMA frame (TO) oftransmission sequence 48. Also shown in FIG. 5, a first frame interrupt(FO) is received immediately prior to transmission of this TO frame.

Still referring to FIG. 5, next a configuration routine 100 (i.e., anuplink AMR configuration routine (ACU)) may be performed duringtransmission of radio block N. As an example, ACU 100 may be scheduledupon receipt of the first frame interrupt FO. In one embodiment, theconfiguration information may first be applied to speech encoder 42 aand then to channel encoder 45 a, although the scope of the presentinvention is not so limited. While the configuration routine 100 may beperformed in various manners, in some embodiments routine 100 may beexecuted in accordance with the flow diagram discussed above withrespect to FIG. 3.

Still referring to FIG. 5, after speech encoder 42 a and channel encoder45 a have been reconfigured with new rate information, speech encodingof radio block N+1 may be performed in speech encoder 42 a duringtransmission of radio block N. Similarly, channel encoding of radioblock N+1 may be performed in channel encoder 45 a and may be completedprior to transmission of radio block N+1. Further, while not shown inFIG. 5, it is to be understood that channel decoding and speech decodingfor radio block N may be performed after receipt of the last burst ofradio block N.

Still referring to FIG. 5, in the downlink direction a configurationroutine 200 (i.e., a downlink AMR configuration routine (ACD)) may beexecuted during transmission of radio block N+1. More specifically, inthe embodiment of FIG. 5, ACD 200 may be scheduled upon receipt of theeighth frame interrupt F7. In one embodiment, configuration routine 200may be performed in accordance with the flow diagram described abovewith respect to FIG. 4. After reconfiguration is completed, channeldecoding for radio block N+1 may occur in channel decoder 45 b and thenspeech decoding for radio block N+1 may occur in speech decoder 42 bSpecifically, decoding may be performed after receipt of the last burstof radio block N+1. Although described in the embodiment of FIG. 5 forreconfiguration, similar activities may be used to configure the channelcodec and vocoder.

Using the embodiments of the present invention, synchronization betweenchannel codec and vocoder may be optimally maintained. Suchsynchronization may further be maintained during configuration, forexample, AMR configuration. Accordingly, embodiments of the presentinvention may be used to maintain the vocoder and channel codec insubstantial synchronization. As used herein, the term “substantial”synchronization means that vocoder and channel codec may be synchronizedto a level at which adverse performance effects are avoided.

The methods described herein may be implemented in software, firmware,and/or hardware. A software implementation may include an article in theform of a machine-readable storage medium onto which there are storedinstructions and data that form a software program to perform suchmethods. As an example, a DSP may include instructions or may beprogrammed with instructions stored in a storage medium to performchannel codec-vocoder synchronization in accordance with an embodimentof the present invention.

Referring now to FIG. 6, shown is a block diagram of a system inaccordance with one embodiment of the present invention. As shown inFIG. 6, system 300 may be a wireless device, such as a cellulartelephone, PDA, portable computer or the like. An antenna 305 is presentto receive and transmit RF signals. Antenna 305 may receive differentbands of incoming RF signals using an antenna switch. For example, aquad-band receiver may be adapted to receive GSM communications,enhanced GSM (EGSM), digital cellular system (DCS) and personalcommunication system (PCS) signals, although the scope of the presentinvention is not so limited. In other embodiments, antenna 305 may beadapted for use in a general packet radio service (GPRS) device, asatellite tuner, or a wireless local area network (WLAN) device, forexample.

Incoming RF signals are provided to a transceiver 310 which may be asingle chip transceiver including both RF components and basebandcomponents. Transceiver 310 may be formed using a complementarymetal-oxide-semiconductor (CMOS) process, in some embodiments. As shownin FIG. 6, transceiver 310 includes an RF transceiver 312 and a basebandprocessor 314. RF transceiver 312 may include receive and transmitportions and may be adapted to provide frequency conversion between theRF spectrum and a baseband. Baseband signals are then provided to abaseband processor 314 for further processing.

In some embodiments, transceiver 310 may correspond to ASIC 15 ofFIG. 1. Baseband processor 314, which may correspond to DSP 10 of FIG.1, may be coupled through a port 318, which in turn may be coupled to aninternal speaker 360 to provide voice data to an end user. Port 318 alsomay be coupled to an internal microphone 370 to receive voice data fromthe end user.

After processing signals received from RF transceiver 312, basebandprocessor 314 may provide such signals to various locations withinsystem 300 including, for example, an application processor 320 and amemory 330. Application processor 320 may be a microprocessor, such as acentral processing unit (CPU) to control operation of system 300 andfurther handle processing of application programs, such as personalinformation management (PIM) programs, email programs, downloaded games,and the like. Memory 330 may include different memory components, suchas a flash memory and a read only memory (ROM), although the scope ofthe present invention is not so limited. Additionally, a display 340 isshown coupled to application processor 320 to provide display ofinformation associated with telephone calls and application programs,for example. Furthermore, a keypad 350 may be present in system 300 toreceive user input.

While the present invention has been described with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations therefrom. It is intended that the appendedclaims cover all such modifications and variations as fall within thetrue spirit and scope of this present invention.

1. An apparatus comprising: a vocoder to encode an audio segment for atransmission; and a channel codec coupled to the vocoder to furtherprocess the coded audio segment, wherein the vocoder and the channelcodec are configured according to a predetermined priority to maintainthe channel codec and the vocoder in substantial synchronization.
 2. Theapparatus of claim 1, wherein the apparatus comprises a digital signalprocessor including the channel codec and the vocoder, and at least oneof the channel codec and the vocoder comprises a software routineexecuted on the digital signal processor.
 3. The apparatus of claim 1,further comprising logic to first configure an encoding portion of thevocoder and an encoding portion of the channel codec according to aconfiguration message and to second configure a decoding portion of thevocoder and a decoding portion of the channel codec according to theconfiguration message.
 4. The apparatus of claim 3, wherein the logic isto configure the encoding portion of the vocoder prior to the encodingportion of the channel codec.
 5. The apparatus of claim 4, wherein thelogic is to configure the decoding portion of the vocoder and thechannel codec after decoding of an audio segment immediately prior to aneffective audio segment set forth in the configuration message.